The present invention relates to disc drive storage devices. More specifically, the present invention relates to a method and apparatus for preventing shorting of a flex circuit head interconnect in a disc drive.
Disc drives are the primary devices employed for mass storage of computer programs and data used in computer systems. Within a disc drive, a load beam supports a hydrodynamic air bearing (or slider) proximate a rotating magnetic disc. The load beam supplies a downward force that counteracts the hydrodynamic lifting force developed by the air bearing. The slider carries a magnetic transducer for communicating with individual positions on the rotating magnetic disc.
In disc drives, it is necessary to electrically couple the magnetic transducer, which is located on the slider above the disc surface, to the electronic circuitry of a disc drive. Traditionally, such interconnection had been effected by running very small wires down the load beam to the magnetic transducer. Although such an approach did create the required electrical connection, it required manual positioning of each individual, fine, wire.
More recently, the interconnection between the magnetic transducer on the head and the disc drive circuitry, has been effected by using flexible circuitry. A flexible circuit (flex circuit) consists of copper traces attached to a polyimide base film. Often, a copper layer is bonded to the polyimide film which copper layer is selectively removed to leave behind copper traces, through conventional photo etch processing. It is common in the flex circuit industry to apply a cover dielectric layer over the copper traces in order to insulate the traces. There are a number of ways to apply such a cover dielectric layer. First, an adhesive coated polyimide film may be laminated to the circuit such that the circuit is essentially sandwiched between the two polyimide films. Alternatively, a cover coat material may be applied as a liquid or laminated as a dry film to the circuit which is then patterned using conventional photo processes.
Although the use of flex circuits for electrical connection between the transducer and the disc drive circuitry has simplified disc drive fabrication, the application of a flex circuit to a head interconnect in a disc drive suffers from limitations.